1. Field of the Invention
This invention relates to the field of heavier-than-air vehicles. More particularly, it relates to the field of hover craft vehicles, such as helicopters, and specifically relates to an improved propulsion and antitorque system therefore.
2. Description of the Prior Art
A helicopter is a heavier-than-air vehicle that can ascend and descend vertically, fly left and right and forward and backward as well as hover motionless in the air. It is generally comprised of a heavier-than-air body having spaced apart front and rear ends, usually termed the nose and the tail, a set of elongated blades of airfoil cross-section, termed main rotor blades extending generally radially in a horizontl plane from a rotor hub located on a rotor mast above the body and adapted to rotate in the generally horizontal plane, a motor or other power means to drive the mast and rotor blades in whirling rotation and develop vertical lift forces than can be applied to the body through the mast, and controls manipulated by the pilot to command it into the air and fly it controlled in virtually any direction. A tail boom extends from the rear part of the body and contains a second (smaller) set of tail rotor blades powered by an elongated drive shaft extending from the main transmission, (which receives power from the engine) along the tail boom to spin the tail rotor in a plane set at a right angle to the plane of the main rotor blades and generally vertical to the plane of the ground.
As the spinning main rotor blades provide vertical lift for the body, and a forward thrust vector of driving force when the plane of the blades is tilted downward toward the nose of the body, a sideways torque or "yaw" is generated that urges the body to rotate about the mast axis in the opposite direction of main rotor blade rotation. This yawing tendency also exists during hovering due to friction and loading in the drive system. The smaller set of tail rotor blades is powered to spin and counter this sideways torque. Depending upon whether the blades are on one side or the other of the tail boom to tail rotor is said to be of the "pusher" or the "puller" type.
The main rotor blades provide all the lift and all the forward thrust to the helicoptor. Because these force directions are at right angles to each other, they combine to develop a bending moment in the main rotor mast. This bending moment, called "mast bending" is generally a limiting factor to the forward speed of the helicopter; to go faster causes more bending in the mast as well as in the main rotor blades and, with any given body weight, exceeding the critical mast bening limit could result in catastrophic collapse of the mast or failure loading of the main rotor blades.
The prior art has attempted to add forward propulsion units to helicopters such as wing mounted, aft thrusting propellers and jets but these have not resulted in any degree of success because of fuel inefficiency and complexity of the propulsion configuration. In addition, these forward propulsion units cause undesirable vibration and stress fatigue in the fuselage or body structure.